﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Code
{
    internal class Encodr
    {
        /// <summary>
        /// 加密类
        /// </summary>
        public class Encodr1
        {
            //3个属性对应明文密文和密钥
            /// <summary>
            /// 明文
            /// </summary>
            public string Plaintext { get; set; }

            /// <summary>
            /// 密钥
            /// </summary>
            public string Key { get; set; }

            /// <summary>
            /// 密文
            /// </summary>
            public string Cypher { get; set; }

            /// <summary>
            /// 加密
            /// </summary>
            public void Encoder()
            {
                Cypher = "";
                //加密过程
                for (int i = 0, j = 0; i < Plaintext.Length; i++, j++)
                {
                    //超过密钥长度部分循环
                    if (j % Key.Length == 0)
                        j = 0;
                    //计算密文
                    int num = (Function(Plaintext[i]) + Function(Key[j])) % 26;
                    Cypher += Convert.ToChar(num + 'a');
                }

            }

            /// <summary>
            /// 返回指定字符在字母表中序号，从0开始
            /// </summary>
            /// <param name="ch"></param>
            /// <returns></returns>
            private int Function(char ch)
            {
                return ch - 'a';
            }
        }
    }
}

